1
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Tian X, Firsanov D, Zhang Z, Cheng Y, Luo L, Tombline G, Tan R, Simon M, Henderson S, Steffan J, Goldfarb A, Tam J, Zheng K, Cornwell A, Johnson A, Yang JN, Mao Z, Manta B, Dang W, Zhang Z, Vijg J, Wolfe A, Moody K, Kennedy BK, Bohmann D, Gladyshev VN, Seluanov A, Gorbunova V. SIRT6 Is Responsible for More Efficient DNA Double-Strand Break Repair in Long-Lived Species. Cell 2019; 177:622-638.e22. [PMID: 31002797 PMCID: PMC6499390 DOI: 10.1016/j.cell.2019.03.043] [Citation(s) in RCA: 186] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 01/22/2019] [Accepted: 03/21/2019] [Indexed: 01/09/2023]
Abstract
DNA repair has been hypothesized to be a longevity determinant, but the evidence for it is based largely on accelerated aging phenotypes of DNA repair mutants. Here, using a panel of 18 rodent species with diverse lifespans, we show that more robust DNA double-strand break (DSB) repair, but not nucleotide excision repair (NER), coevolves with longevity. Evolution of NER, unlike DSB, is shaped primarily by sunlight exposure. We further show that the capacity of the SIRT6 protein to promote DSB repair accounts for a major part of the variation in DSB repair efficacy between short- and long-lived species. We dissected the molecular differences between a weak (mouse) and a strong (beaver) SIRT6 protein and identified five amino acid residues that are fully responsible for their differential activities. Our findings demonstrate that DSB repair and SIRT6 have been optimized during the evolution of longevity, which provides new targets for anti-aging interventions.
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Affiliation(s)
- Xiao Tian
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Denis Firsanov
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Zhihui Zhang
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Yang Cheng
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Lingfeng Luo
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Gregory Tombline
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Ruiyue Tan
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Matthew Simon
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Steven Henderson
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Janine Steffan
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Audrey Goldfarb
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Jonathan Tam
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Kitty Zheng
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Adam Cornwell
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Adam Johnson
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Jiang-Nan Yang
- Leibniz Institute on Aging - Fritz Lipmann Institute, Beutenbergstraße 11, Jena D-07745, Germany
| | - Zhiyong Mao
- School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Bruno Manta
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Weiwei Dang
- Huffington Center on Aging, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhengdong Zhang
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jan Vijg
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Aaron Wolfe
- Ichor Therapeutics, 2521 US-11, Lafayette, NY 13084, USA
| | - Kelsey Moody
- Ichor Therapeutics, 2521 US-11, Lafayette, NY 13084, USA
| | - Brian K Kennedy
- Departments of Biochemistry and Physiology, National University Singapore, Singapore; Centre for Healthy Aging, National University Health System, Singapore
| | - Dirk Bohmann
- Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Vadim N Gladyshev
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Andrei Seluanov
- Department of Biology, University of Rochester, Rochester, NY 14627, USA.
| | - Vera Gorbunova
- Department of Biology, University of Rochester, Rochester, NY 14627, USA.
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2
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The extent of liver injury determines hepatocyte fate toward senescence or cancer. Cell Death Dis 2018; 9:575. [PMID: 29760381 PMCID: PMC5951829 DOI: 10.1038/s41419-018-0622-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/22/2018] [Accepted: 04/24/2018] [Indexed: 12/13/2022]
Abstract
It is well known that induction of hepatocyte senescence could inhibit the development of hepatocellular carcinoma (HCC). Until now, it is still unclear how the degree of liver injury dictates hepatocyte senescence and carcinogenesis. In this study, we investigated whether the severity of injury determines cell fate decisions between hepatocyte senescence and carcinogenesis. After testing of different degrees of liver injury, we found that hepatocyte senescence is strongly induced in the setting of severe acute liver injury. Longer-term, moderate liver injury, on the contrary did not result into hepatocyte senescence, but led to a significant incidence of HCC instead. In addition, carcinogenesis was significantly reduced by the induction of severe acute injury after chronic moderate liver injury. Meanwhile, immune surveillance, especially the activations of macrophages, was activated after re-induction of senescence by severe acute liver injury. We conclude that severe acute liver injury leads to hepatocyte senescence along with activating immune surveillance and a low incidence of HCC, whereas chronic moderate injury allows hepatocytes to proliferate rather than to enter into senescence, and correlates with a high incidence of HCC. This study improves our understanding in hepatocyte cell fate decisions and suggests a potential clinical strategy to induce senescence to treat HCC.
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Kubben N, Misteli T. Shared molecular and cellular mechanisms of premature ageing and ageing-associated diseases. Nat Rev Mol Cell Biol 2017; 18:595-609. [PMID: 28792007 DOI: 10.1038/nrm.2017.68] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ageing is the predominant risk factor for many common diseases. Human premature ageing diseases are powerful model systems to identify and characterize cellular mechanisms that underpin physiological ageing. Their study also leads to a better understanding of the causes, drivers and potential therapeutic strategies of common diseases associated with ageing, including neurological disorders, diabetes, cardiovascular diseases and cancer. Using the rare premature ageing disorder Hutchinson-Gilford progeria syndrome as a paradigm, we discuss here the shared mechanisms between premature ageing and ageing-associated diseases, including defects in genetic, epigenetic and metabolic pathways; mitochondrial and protein homeostasis; cell cycle; and stem cell-regenerative capacity.
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Affiliation(s)
- Nard Kubben
- National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Tom Misteli
- National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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4
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Gorbunova V, Seluanov A. DNA double strand break repair, aging and the chromatin connection. Mutat Res 2016; 788:2-6. [PMID: 26923716 DOI: 10.1016/j.mrfmmm.2016.02.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 02/01/2016] [Accepted: 02/10/2016] [Indexed: 01/07/2023]
Abstract
Are DNA damage and mutations possible causes or consequences of aging? This question has been hotly debated by biogerontologists for decades. The importance of DNA damage as a possible driver of the aging process went from being widely recognized to then forgotten, and is now slowly making a comeback. DNA double strand breaks (DSBs) are particularly relevant to aging because of their toxicity, increased frequency with age and the association of defects in their repair with premature aging. Recent studies expand the potential impact of DNA damage and mutations on aging by linking DNA DSB repair and age-related chromatin changes. There is overwhelming evidence that increased DNA damage and mutations accelerate aging. However, an ultimate proof of causality would be to show that enhanced genome and epigenome stability delays aging. This is not an easy task, as improving such complex biological processes is infinitely more difficult than disabling it. We will discuss the possibility that animal models with enhanced DNA repair and epigenome maintenance will be generated in the near future.
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Affiliation(s)
- Vera Gorbunova
- University of Rochester, Department of Biology, Hutchison Hall, RC, Rochester, NY 14627, USA.
| | - Andrei Seluanov
- University of Rochester, Department of Biology, Hutchison Hall, RC, Rochester, NY 14627, USA
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Wang MJ, Chen F, Li JX, Liu CC, Zhang HB, Xia Y, Yu B, You P, Xiang D, Lu L, Yao H, Borjigin U, Yang GS, Wangensteen KJ, He ZY, Wang X, Hu YP. Reversal of hepatocyte senescence after continuous in vivo cell proliferation. Hepatology 2014; 60:349-61. [PMID: 24711261 DOI: 10.1002/hep.27094] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 02/20/2014] [Indexed: 12/18/2022]
Abstract
UNLABELLED A better understanding of hepatocyte senescence could be used to treat age-dependent disease processes of the liver. Whether continuously proliferating hepatocytes could avoid or reverse senescence has not yet been fully elucidated. We confirmed that the livers of aged mice accumulated senescent and polyploid hepatocytes, which is associated with accumulation of DNA damage and activation of p53-p21 and p16(ink4a)-pRB pathways. Induction of multiple rounds continuous cell division is hard to apply in any animal model. Taking advantage of serial hepatocyte transplantation assays in the fumarylacetoacetate hydrolase-deficient (Fah(-/-)) mouse, we studied the senescence of hepatocytes that had undergone continuous cell proliferation over a long time period, up to 12 rounds of serial transplantations. We demonstrated that the continuously proliferating hepatocytes avoided senescence and always maintained a youthful state. The reactivation of telomerase in hepatocytes after serial transplantation correlated with reversal of senescence. Moreover, senescent hepatocytes harvested from aged mice became rejuvenated upon serial transplantation, with full restoration of proliferative capacity. The same findings were also true for human hepatocytes. After serial transplantation, the high initial proportion of octoploid hepatocytes decreased to match the low level of youthful liver. CONCLUSION These findings suggest that the hepatocyte "ploidy conveyer" is regulated differently during aging and regeneration. The findings of reversal of hepatocyte senescence could enable future studies on liver aging and cell therapy.
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Affiliation(s)
- Min-Jun Wang
- Department of Cell Biology, Second Military Medical University, Shanghai, P.R. China; Center for Stem Cell and Medicine, Graduate School, Second Military Medical University, Shanghai, P.R. China
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6
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Metabolism, genomics, and DNA repair in the mouse aging liver. Curr Gerontol Geriatr Res 2011; 2011:859415. [PMID: 21559242 PMCID: PMC3087416 DOI: 10.1155/2011/859415] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 02/11/2011] [Indexed: 12/22/2022] Open
Abstract
The liver plays a pivotal role in the metabolism of nutrients, drugs, hormones, and metabolic waste products, thereby maintaining body homeostasis. The liver undergoes substantial changes in structure and function within old age. Such changes are associated with significant impairment of many hepatic metabolic and detoxification activities, with implications for systemic aging and age-related disease. It has become clear, using rodent models as biological tools, that genetic instability in the form of gross DNA rearrangements or point mutations accumulate in the liver with age. DNA lesions, such as oxidized bases or persistent breaks, increase with age and correlate well with the presence of senescent hepatocytes. The level of DNA damage and/or mutation can be affected by changes in carcinogen activation, decreased ability to repair DNA, or a combination of these factors. This paper covers some of the DNA repair pathways affecting liver homeostasis with age using rodents as model systems.
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7
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Valentine CR, Delongchamp RR, Pearce MG, Rainey HF, Dobrovolsky VN, Malling HV, Heflich RH. In vivo mutation analysis using the ΦX174 transgenic mouse and comparisons with other transgenes and endogenous genes. Mutat Res 2010; 705:205-16. [PMID: 20637298 DOI: 10.1016/j.mrrev.2010.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 06/24/2010] [Accepted: 07/02/2010] [Indexed: 01/01/2023]
Abstract
The ΦX174 transgenic mouse was first developed as an in vivo Ames test, detecting base pair substitution (bps) at a single bp in a reversion assay. A forward mutational assay was also developed, which is a gain of function assay that also detects bps exclusively. Later work with both assays focused on establishing that a mutation was fixed in vivo using single-burst analysis: determining the number of mutant progeny virus from an electroporated cell by dividing the culture into aliquots before scoring mutants. We review results obtained from single-burst analysis, including testing the hypothesis that high mutant frequencies (MFs) of G:C to A:T mutation recovered by transgenic targets include significant numbers of unrepaired G:T mismatches. Comparison between the ΦX174 and lacI transgenes in mouse spleen indicates that the spontaneous bps mutation frequency per nucleotide (mf(n)) is not significantly lower for ΦX174 than for lacI; the response to ENU is also comparable. For the lacI transgene, the spontaneous bps mf(n) is highly age-dependent up to 12 weeks of age and the linear trend extrapolates at conception to a frequency close to the human bps mf(n) per generation of 1.7 × 10(-8). Unexpectedly, we found that the lacI somatic (spleen) bps mf(n) per cell division at early ages was estimated to be the same as for the human germ-line. The bps mf(n) in bone marrow for the gpt transgene is comparable to spleen for the lacI and ΦX174 transgenes. We conclude that the G:C to A:T transition is characteristic of spontaneous in vivo mutation and that the MFs measured in these transgenes at early ages reflect the expected accumulation of in vivo mutation typical of endogenous mammalian mutation rates. However, spontaneous and induced mf(n)s per nucleotide for the cII gene in spleen are 5-10 times higher than for these other transgenes.
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Affiliation(s)
- Carrie R Valentine
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, 3900 NCTR Road, HFT-120, Jefferson, AR 72079, USA
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8
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Wang J, Chen T. Sequencing analysis of mutations induced by N-ethyl-N-nitrosourea at different sampling times in mouse bone marrow. J Appl Toxicol 2009; 30:133-41. [PMID: 19764070 DOI: 10.1002/jat.1479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In our previous study (Wang et al., 2004, Toxicol. Sci. 82: 124-128), we observed that the cII gene mutant frequency (MF) in the bone marrow of Big Blue mice showed significant increase as early as day 1, reached the maximum at day 3 and then decreased to a plateau by day 15 after a single dose of carcinogen N-ethyl-N-nitrosourea (ENU) treatment, which is different from the longer mutation manifestation time and the constancy of MFs after reaching their maximum in some other tissues. To determine the mechanism underlying the quick increase in MF and the peak formation in the mutant manifestation, we examined the mutation frequencies and spectra of the ENU-induced mutants collected from different sampling times in this study. The cII mutants from days 1, 3 and 120 after ENU treatment were randomly selected from different animals. The mutation frequencies were 33, 217, 305 and 144 x 10(-6) for control, days 1, 3, and 120, respectively. The mutation spectra at days 1 and 3 were significantly different from that at day 120. Considering that stem cells are responsible for the ultimate MF plateau (day 120) and transit cells are accountable for the earlier MF induction (days 1 or 3) in mouse bone marrow, we conclude that transit cells are much more sensitive to mutation induction than stem cells in mouse bone marrow, which resulted in the specific mutation manifestation induced by ENU.
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Affiliation(s)
- Jianyong Wang
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR 72079, USA
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10
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Xu G, Herzig M, Rotrekl V, Walter CA. Base excision repair, aging and health span. Mech Ageing Dev 2008; 129:366-82. [PMID: 18423806 PMCID: PMC2526234 DOI: 10.1016/j.mad.2008.03.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 02/28/2008] [Accepted: 03/05/2008] [Indexed: 12/18/2022]
Abstract
DNA damage and mutagenesis are suggested to contribute to aging through their ability to mediate cellular dysfunction. The base excision repair (BER) pathway ameliorates a large number of DNA lesions that arise spontaneously. Many of these lesions are reported to increase with age. Oxidized guanine, repaired largely via base excision repair, is particularly well studied and shown to increase with age. Spontaneous mutant frequencies also increase with age which suggests that mutagenesis may contribute to aging. It is widely accepted that genetic instability contributes to age-related occurrences of cancer and potentially other age-related pathologies. BER activity decreases with age in multiple tissues. The specific BER protein that appears to limit activity varies among tissues. DNA polymerase-beta is reduced in brain from aged mice and rats while AP endonuclease is reduced in spermatogenic cells obtained from old mice. The differences in proteins that appear to limit BER activity among tissues may represent true tissue-specific differences in activity or may be due to differences in techniques, environmental conditions or other unidentified differences among the experimental approaches. Much remains to be addressed concerning the potential role of BER in aging and age-related health span.
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Affiliation(s)
- Guogang Xu
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
| | - Maryanne Herzig
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
| | - Vladimir Rotrekl
- Institute of Experimental Medicine, Department of Molecular Embryology, Masaryk University, Faculty of Medicine, Department of Biology, Kamenice 5, Building A6, 62500 Brno, Czech Republic
| | - Christi A. Walter
- Department of Cellular & Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900
- South Texas Veteran’s Health Care System, 7400 Merton Minter Blvd, San Antonio, TX 78229
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11
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Fein M, Peters JH, DeMeester TR. Carcinogenesis in reflux disease--in search for bile-specific effects. Microsurgery 2008; 27:647-50. [PMID: 17929260 DOI: 10.1002/micr.20424] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Bile reflux may play a key role for esophageal carcinogenesis in reflux disease. In search for bile-specific effects, the animal model of esophageal cancer was applied in a mutagenesis assay. Big Blue transgenic mice were operated with microsurgical techniques. Seven had total gastrectomy with esophagojejunostomy creating esophageal reflux of bile and five had a sham operation. After 24 weeks, the mutation frequency (MF) was measured through standard Big Blue mutagenesis assay in the esophageal mucosa and the duodenum as control. Esophageal reflux resulted in esophagitis in the distal esophagus. The MF in esophageal mucosa was 1.6 times higher in animals with reflux than in sham-operated animals; it was identical in the duodenum. In conclusion, the mutagenic potential of bile reflux has been confirmed. However, mechanisms of carcinogenesis in the esophageal cancer model other than chronic inflammation could not be identified because of the only moderately increased MF.
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Affiliation(s)
- Martin Fein
- Department of Surgery, University of Wuerzburg, Wuerzburg, Germany.
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12
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Michod RE, Bernstein H, Nedelcu AM. Adaptive value of sex in microbial pathogens. INFECTION GENETICS AND EVOLUTION 2008; 8:267-85. [PMID: 18295550 DOI: 10.1016/j.meegid.2008.01.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 12/30/2007] [Accepted: 01/02/2008] [Indexed: 12/16/2022]
Abstract
Explaining the adaptive value of sex is one of the great outstanding problems in biology. The challenge comes from the difficulty in identifying the benefits provided by sex, which must outweigh the substantial costs of sex. Here, we consider the adaptive value of sex in viruses, bacteria and fungi, and particularly the information available on the adaptive role of sex in pathogenic microorganisms. Our general theme is that the varied aspects of sex in pathogens illustrate the varied issues surrounding the evolution of sex generally. These include, the benefits of sex (in the short- and long-term), as well as the costs of sex (both to the host and to the pathogen). For the benefits of sex (that is, its adaptive value), we consider three hypotheses: (i) sex provides for effective and efficient recombinational repair of DNA damages, (ii) sex provides DNA for food, and (iii) sex produces variation and reduces genetic associations among alleles under selection. Although the evolution of sex in microbial pathogens illustrates these general issues, our paper is not a general review of theories for the evolution of sex in all organisms. Rather, we focus on the adaptive value of sex in microbial pathogens and conclude that in terms of short-term benefits, the DNA repair hypothesis has the most support and is the most generally applicable hypothesis in this group. In particular, recombinational repair of DNA damages may substantially benefit pathogens when challenged by the oxidative defenses of the host. However, in the long-term, sex may help get rid of mutations, increase the rate of adaptation of the population, and, in pathogens, may infrequently create new infective strains. An additional general issue about sex illustrated by pathogens is that some of the most interesting consequences of sex are not necessarily the reasons for which sex evolved. For example, antibiotic resistance may be transferred by bacterial sex, but this transfer is probably not the reason sex evolved in bacteria.
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Affiliation(s)
- Richard E Michod
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson 85721, USA.
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Ribeiro ML, Arçari DP, Squassoni AC, Pedrazzoli J. Effects of multivitamin supplementation on DNA damage in lymphocytes from elderly volunteers. Mech Ageing Dev 2007; 128:577-80. [PMID: 17884137 DOI: 10.1016/j.mad.2007.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 08/07/2007] [Accepted: 08/09/2007] [Indexed: 11/16/2022]
Abstract
The aim of this study was to evaluate the effect of a mixture of vitamins and minerals on oxidative DNA damage and the resistance of DNA to H(2)O(2)-induced DNA strand breaks in lymphocytes from 80 elderly volunteers ex vivo by means of Comet assay. The intervention with vitamin complex decreased significantly the levels of DNA damage. Our results demonstrate that the vitamin complex was able to decrease H(2)O(2)-induced DNA breakage. Our data suggest that the consumption of some vitamins may reduce the effects of oxidative DNA damage and may be useful for attaining healthy aging.
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Affiliation(s)
- Marcelo Lima Ribeiro
- Unidade Integrada de Farmacologia e Gastroenterologia, Universidade São Francisco, Av. São Francisco de Assis, 218. Jd. São José, Bragança Paulista, SP, Brazil.
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14
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Wang J, Gonzalez KD, Scaringe WA, Tsai K, Liu N, Gu D, Li W, Hill KA, Sommer SS. Evidence for mutation showers. Proc Natl Acad Sci U S A 2007; 104:8403-8. [PMID: 17485671 PMCID: PMC1895962 DOI: 10.1073/pnas.0610902104] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutants in the Big Blue transgenic mouse system show spontaneous clustered multiple mutations with unexpectedly high frequency, consistent with chronocoordinate events. We tested the prediction that the multiple mutations seen within the lacI mutation target sometimes occur in the context of chronocoordinate multiple mutations spanning multiple kilobases (mutation showers). Additional sequencing of mutants was performed in regions immediately flanking the lacI region (total of 10.7 kb). Nineteen additional mutations were found outside the lacI region ("ectomutations") from 10 mutants containing two or more lacI mutations, whereas only one ectomutation was found in 130 mutants with a single mutation (P < 0.0001). The mutation showers had an average of approximately one mutation per 3 kb. Four mutants showed closely spaced double mutations in the new sequence, and analysis of the spacing between these mutations revealed significant clustering (P = 0.0098). To determine the extent of the mutation showers, regions (8.5 kb total) remote from the lacI region (approximately 16-17 kb away) were sequenced. Only two additional ectomutations were found in these remote regions, consistent with mutation showers that generally do not extend more than approximately 30 kb. We conclude that mutation showers exist and that they constitute at least 0.2% and possibly 1% or more of mutational events observed in this system. The existence of mutation showers has implications for oncogenesis and evolution, raising the possibilities of "cancer in an instant" and "introns as sponges to reduce the deleterious impact of mutation showers."
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Affiliation(s)
| | | | - William A. Scaringe
- *Department of Molecular Genetics and
- Bioinformatics Group, Department of Molecular Genetics, City of Hope National Medical Center, Duarte, CA 91010; and
| | | | - Ning Liu
- *Department of Molecular Genetics and
| | - Dongqing Gu
- *Department of Molecular Genetics and
- Bioinformatics Group, Department of Molecular Genetics, City of Hope National Medical Center, Duarte, CA 91010; and
| | - Wenyan Li
- *Department of Molecular Genetics and
| | - Kathleen A. Hill
- *Department of Molecular Genetics and
- Department of Biology, University of Western Ontario, London, ON, CanadaN6A 5B7
| | - Steve S. Sommer
- *Department of Molecular Genetics and
- To whom correspondence should be addressed at:
Beckman Research Institute/City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA 91010-0269. E-mail:
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15
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Genescà A, Martín M, Latre L, Soler D, Pampalona J, Tusell L. Telomere dysfunction: a new player in radiation sensitivity. Bioessays 2006; 28:1172-80. [PMID: 17120191 DOI: 10.1002/bies.20501] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Human individuals often exhibit important differences in their sensitivity to ionising radiation. Extensive literature links radiation sensitivity with impaired DNA repair which is due to a lack of correct functioning in many proteins involved in DNA-repair pathways and/or in DNA-damage checkpoint responses. Given that ionising radiation is an important and widespread diagnostic and therapeutic tool, it is important to investigate further those factors and mechanisms that underlie individual radiosensitivity. Recently, evidence is accumulating that telomere function may well be involved in cellular and organism responses to ionising radiation, broadening still further the currently complex and challenging scenario.
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Affiliation(s)
- Anna Genescà
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Spain.
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16
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Parsons BL, Delongchamp RR, Beland FA, Heflich RH. Levels of H-ras codon 61 CAA to AAA mutation: response to 4-ABP-treatment and Pms2-deficiency. Mutagenesis 2005; 21:29-34. [PMID: 16314341 DOI: 10.1093/mutage/gei066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
DNA mismatch repair (MMR) deficiencies result in increased frequencies of spontaneous mutation and tumor formation. In the present study, we tested the hypothesis that a chemically-induced mutational response would be greater in a mouse with an MMR-deficiency than in the MMR-proficient mouse models commonly used to assay for chemical carcinogenicity. To accomplish this, the induction of H-ras codon 61 CAA-->AAA mutation was examined in Pms2 knockout mice (Pms2-/-, C57BL/6 background) and sibling wild-type mice (Pms2+/+). Groups of five or six neonatal male mice were treated with 0.3 micromol 4-aminobiphenyl (4-ABP) or the vehicle control, dimethylsulfoxide. Eight months after treatment, liver DNAs were isolated and analysed for levels of H-ras codon 61 CAA-->AAA mutation using allele-specific competitive blocker-PCR. In Pms2-proficient and Pms2-deficient mice, 4-ABP treatment caused an increase in mutant fraction (MF) from 1.65x10(-5) to 2.91x10(-5) and from 3.40x10(-5) to 4.70x10(-5), respectively. Pooling data from 4-ABP-treated and control mice, the approximately 2-fold increase in MF observed in Pms2-deficient as compared with Pms2-proficient mice was statistically significant (P=0.0207) and consistent with what has been reported previously in terms of induction of G:C-->T:A mutation in a Pms2-deficient background. Pooling data from both genotypes, the increase in H-ras MF in 4-ABP-treated mice, as compared with control mice, did not reach the 95% confidence level of statistical significance (P=0.0606). The 4-ABP treatment caused a 1.76-fold and 1.38-fold increase in average H-ras MF in Pms2-proficient and Pms2-deficient mice, respectively. Furthermore, the levels of induced mutation in Pms2-proficient and Pms2-deficient mice were nearly identical (1.26x10(-5) and 1.30x10(-5), respectively). We conclude that Pms2-deficiency does not result in an amplification of the H-ras codon 61 CAA-->AAA mutational response induced by 4-ABP.
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Affiliation(s)
- Barbara L Parsons
- Division of Genetic and Reproductive Toxicology, Division of Biometry and Risk Assessment and Division of Biochemical Toxicology, National Center for Toxicological Research, USFDA, Jefferson, AR 72079, USA.
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17
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Lambert IB, Singer TM, Boucher SE, Douglas GR. Detailed review of transgenic rodent mutation assays. Mutat Res 2005; 590:1-280. [PMID: 16081315 DOI: 10.1016/j.mrrev.2005.04.002] [Citation(s) in RCA: 252] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2005] [Revised: 04/04/2005] [Accepted: 04/12/2005] [Indexed: 11/17/2022]
Abstract
Induced chromosomal and gene mutations play a role in carcinogenesis and may be involved in the production of birth defects and other disease conditions. While it is widely accepted that in vivo mutation assays are more relevant to the human condition than are in vitro assays, our ability to evaluate mutagenesis in vivo in a broad range of tissues has historically been quite limited. The development of transgenic rodent (TGR) mutation models has given us the ability to detect, quantify, and sequence mutations in a range of somatic and germ cells. This document provides a comprehensive review of the TGR mutation assay literature and assesses the potential use of these assays in a regulatory context. The information is arranged as follows. (1) TGR mutagenicity models and their use for the analysis of gene and chromosomal mutation are fully described. (2) The principles underlying current OECD tests for the assessment of genotoxicity in vitro and in vivo, and also nontransgenic assays available for assessment of gene mutation, are described. (3) All available information pertaining to the conduct of TGR assays and important parameters of assay performance have been tabulated and analyzed. (4) The performance of TGR assays, both in isolation and as part of a battery of in vitro and in vivo short-term genotoxicity tests, in predicting carcinogenicity is described. (5) Recommendations are made regarding the experimental parameters for TGR assays, and the use of TGR assays in a regulatory context.
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Affiliation(s)
- Iain B Lambert
- Mutagenesis Section, Environmental Health Sciences Bureau, Healthy Environments and Consumer Safety Branch, 0803A, Health Canada, Ottawa, Ont., Canada K1A 0L2.
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Mei N, Heflich RH, Moore MM, Chen T. Age-dependent sensitivity of Big Blue transgenic mice to the mutagenicity of N-ethyl-N-nitrosourea (ENU) in liver. Mutat Res 2005; 572:14-26. [PMID: 15790487 PMCID: PMC6441962 DOI: 10.1016/j.mrfmmm.2004.11.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 11/03/2004] [Accepted: 11/14/2004] [Indexed: 10/25/2022]
Abstract
The incidence of childhood cancer is increasing and recent evidence suggests an association between childhood cancer and environmental exposure to genotoxins. In the present study, the Big Blue transgenic mouse model was used to determine whether specific periods in early life represent windows of vulnerability to mutation induction by genotoxins in mouse liver. Groups of mice were treated with single doses of 120 mg N-ethyl-N-nitrosourea (ENU)/kg body weight or the vehicle either transplacentally to the 18-day-old fetus or at postnatal days (PNDs) 1, 8, 15, 42 or 126; the animals were sacrificed 6 weeks after their treatment. The cII mutation assay was performed to determine the mutant frequencies (MFs) in the livers of the mice. Liver cII MFs for both sexes were dependent on the age at which the animals were treated. Perinatal treatment with ENU (either transplacental treatment to the 18-day-old fetus or i.p. injection at PND 1) induced relatively high MFs. However, ENU treatment at PNDs 8 and 15 resulted in the highest mutation induction. The lowest mutation induction occurred in those animals treated as adults (PND 126). For instance, the cII MF for the PND 8 female group was 646 x 10(-6) while the MF for female adults was only 145 x 10(-6), a more than 4-fold difference. Molecular analysis of the mutants found that A:T-->T:A transversions and A:T-->G:C transitions characterized the pattern of mutations induced by ENU in both the neonate and adult mice, while the predominate type of mutation in the controls was G:C-->A:T. The results indicate that mouse liver is most sensitive to ENU-induced mutation during infancy. This period correlates well with the age-dependent sensitivity to carcinogenicity in mouse liver, suggesting that mutation is an important rate-limiting factor for age-related carcinogenesis.
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Affiliation(s)
| | | | | | - Tao Chen
- Corresponding author. Tel.: +1 870 543 7954; fax: +1 870 543 7682. (T. Chen)
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19
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Parsons BL, Beland FA, Von Tungeln LS, Delongchamp RR, Fu PP, Heflich RH. Levels of 4-aminobiphenyl-induced somatic H-ras mutation in mouse liver DNA correlate with potential for liver tumor development. Mol Carcinog 2005; 42:193-201. [PMID: 15761837 DOI: 10.1002/mc.20083] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The utility of liver H-ras codon 61 CAA to AAA mutant fraction as a biomarker of liver tumor development was investigated using neonatal male mice treated with 4-aminobiphenyl (4-ABP). Treatment with 0.1, 0.3, or 1.0 mumol 4-ABP produced dose-dependent increases in liver DNA adducts in B6C3F(1) and C57BL/6N mice. Eight months after treatment with 0.3 mumol 4-ABP or the DMSO vehicle, H-ras codon 61 CAA to AAA mutant fraction was measured in liver DNA samples (n = 12) by allele-specific competitive blocker-polymerase chain reaction (ACB-PCR). A significant increase in average mutant fraction was found in DNA of 4-ABP-treated mice, with an increase from 1.3 x 10(-5) (control) to 44.9 x 10(-5) (treated) in B6C3F(1) mice and from 1.4 x 10(-5) to 7.0 x 10(-5) in C57BL/6N mice. Compared with C57BL/6N mutant fractions, B6C3F(1) mutant fractions were more variable and included some particularly high mutant fractions, consistent with the more rapid development of liver foci expected in B6C3F(1) mouse liver. Twelve months after treatment, liver tumors developed in 79.2% of 4-ABP-treated and 22.2% of control B6C3F(1) mice; thus measurement of H-ras mutant fraction correlated with subsequent tumor development. This study demonstrates that ACB-PCR can directly measure background levels of somatic oncogene mutation and detect a carcinogen-induced increase in such mutation.
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Affiliation(s)
- Barbara L Parsons
- Division of Genetic and Reproductive Toxicology, US FDA National Center for Toxicological Research, 3900 NCTR Road, Jefferson, AR 72079, USA
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20
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Gorbunova V, Seluanov A. Making ends meet in old age: DSB repair and aging. Mech Ageing Dev 2005; 126:621-8. [PMID: 15888314 DOI: 10.1016/j.mad.2005.02.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 02/14/2005] [Accepted: 02/14/2005] [Indexed: 01/10/2023]
Abstract
Accumulation of somatic mutations has long been considered as a major cause of aging and age-related diseases such as cancer. Genomic rearrangements, which arise from aberrant repair of DNA breaks, are the most characteristic component of the mutation spectra in aging cells and tissues. The studies conducted in the past few years provide further support for the role of DNA double-strand break (DSB) repair in aging and cellular senescence. Evidence was obtained that in addition to accumulation of mutations the efficiency and fidelity of repair declines with age. We propose that DNA damage and age-related decline of DNA repair form a vicious cycle leading to amplification of damage and progression of aging, and discuss a hypothesis on how the interplay between the two pathways of DSB repair, homologous recombination and nonhomologous end joining, may contribute to the aging process.
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Affiliation(s)
- Vera Gorbunova
- Department of Biology, University of Rochester, NY 14627, USA.
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21
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Bailey KJ, Maslov AY, Pruitt SC. Accumulation of mutations and somatic selection in aging neural stem/progenitor cells. Aging Cell 2004; 3:391-7. [PMID: 15569356 DOI: 10.1111/j.1474-9728.2004.00128.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Genomic instability within somatic stem cells may lead to the accumulation of mutations and contribute to cancer or other age-related phenotypes. However, determining the frequency of mutations that differ among individual stem cells is difficult from whole tissue samples because each event is diluted in the total population of both stem cells and differentiated tissue. Here the ability to expand neural stem/progenitor cells clonally permitted measurement of genomic alterations derived from a single initial cell. C57Bl/6 x DBA/2 hybrid mice were used and PCR analysis with strain-specific primers was performed to detect loss of heterozygosity on nine different chromosomes for each neurosphere. The frequency with which changes occurred in neurospheres derived from 2-month- and 2-year-old mice was compared. In 15 neurospheres derived from young animals both parental chromosomes were present for all nine chromosome pairs. In contrast, 16/17 neurospheres from old animals demonstrated loss of heterozygosity (LOH) on one or more chromosomes and seven exhibited a complete deletion of at least one chromosomal region. For chromosomes 9 and 19 there is a significant bias in the allele that is lost where in each case the C57Bl/6 allele is retained in 6/6 neurospheres exhibiting LOH. These data suggest that aging leads to a substantial mutational load within the neural stem cell compartment which can be expected to affect the normal function of these cells. Furthermore, the retention of specific alleles for chromosomes 9 and 19 suggests that a subset of mutational events lead to an allele-specific survival advantage within the neural stem cell compartment.
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Affiliation(s)
- Kimberly J Bailey
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
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22
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Seluanov A, Mittelman D, Pereira-Smith OM, Wilson JH, Gorbunova V. DNA end joining becomes less efficient and more error-prone during cellular senescence. Proc Natl Acad Sci U S A 2004; 101:7624-9. [PMID: 15123826 PMCID: PMC419656 DOI: 10.1073/pnas.0400726101] [Citation(s) in RCA: 222] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Accepted: 03/29/2004] [Indexed: 12/29/2022] Open
Abstract
Accumulation of somatic mutations is thought to contribute to the aging process. Genomic instability has been shown to increase during aging, suggesting an aberrant function of DNA double-strand break (DSB) repair. Surprisingly, DSB repair has not been examined with respect to cellular senescence. Therefore, we have studied the ability of young, presenescent, and senescent normal human fibroblasts to repair DSBs in transfected DNA by using a fluorescent reporter substrate. We have found that the efficiency of end joining is reduced up to 4.5 fold in presenescent and senescent cells, relative to young cells. Sequence analysis of end junctions showed that the frequency of precise ligation was higher in young cells, whereas end joining in old cells was associated with extended deletions. These results indicate that end joining becomes inefficient and more error-prone during cellular senescence. Furthermore, the ability to use microhomologies for end joining was compromised in senescent cells, suggesting that young and senescent cells may use different end joining pathways. We hypothesize that inefficient and aberrant end joining is a likely mechanism underlying the age-related genomic instability and higher incidence of cancer in the elderly.
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Affiliation(s)
- Andrei Seluanov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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23
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Valentine CR, Raney JL, Shaddock JG, Dobrovolsky VN, Delongchamp RR. In vivo mutation in gene A of splenic lymphocytes from phiX174 transgenic mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2004; 44:128-150. [PMID: 15278917 DOI: 10.1002/em.20043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Single-burst analysis was applied to a forward assay for gene A mutation in splenic lymphocytes of phiX174 transgenic mice for the purpose of optimizing analytical parameters for identifying in vivo mutations. The effect of varying the cutoff value for an in vivo burst on induced mutant frequency, fold increase, and the significance of the difference between control and N-ethyl-N-nitrosourea (ENU)-treated mice was calculated by two different methods. The plating density was reduced to an average of less than 10 background mutant plaques per aliquot in order to separate in vitro bursts. The spectrum of mutations contributing < 60 plaques per aliquot from control animals was not significantly different from the control spectra from E. coli or transgenic phiX174 cells in culture. The mutant spectra from ENU-treated animals was highly different between mutant bursts of > 80 plaques per aliquot compared to mutations contributing < 60 plaques per aliquot (P < 0.000001), the former fitting the spectrum expected for ENU-induced mutations. The latter spectrum was also different from control animals and E. coli (P < 0.000001), suggesting the difference was caused by ex vivo mutation. With the mutations found in this study, the total number of reported target sites for gene A is now 33. The results support the interpretation that, in contrast to results for the lacI transgene, 100% of mutants isolated in gene A from control animals and cells were fixed in E. coli. We attribute the difference between the two genes to hot-spot sites for mutation in gene A and to a testable hypothesis that the mosaic plaque assay for the lacI transgene underestimates the frequency of ex vivo mutants.
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Affiliation(s)
- Carrie R Valentine
- Division of Genetic and Reproductive Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
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24
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Abstract
Mutation rate is an essential parameter in genetic research. Counting the number of mutant individuals provides information for a direct estimate of mutation rate. However, mutant individuals in the same family can share the same mutations due to premeiotic mutation events, so that the number of mutant individuals can be significantly larger than the number of mutation events observed. Since mutation rate is more closely related to the number of mutation events, whether one should count only independent mutation events or the number of mutants remains controversial. We show in this article that counting mutant individuals is a correct approach for estimating mutation rate, while counting only mutation events will result in underestimation. We also derived the variance of the mutation-rate estimate, which allows us to examine a number of important issues about the design of such experiments. The general strategy of such an experiment should be to sample as many families as possible and not to sample much more offspring per family than the reciprocal of the pairwise correlation coefficient within each family. To obtain a reasonably accurate estimate of mutation rate, the number of sampled families needs to be in the same or higher order of magnitude as the reciprocal of the mutation rate.
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Affiliation(s)
- Yun-Xin Fu
- Human Genetics Center, University of Texas, Houston 77030, USA.
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25
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Hersh MN, Stambrook PJ, Stringer JR. Visualization of mosaicism in tissues of normal and mismatch-repair-deficient mice carrying a microsatellite-containing transgene. Mutat Res 2002; 505:51-62. [PMID: 12175905 DOI: 10.1016/s0027-5107(02)00120-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To determine the frequency of mutation in different cell types of mammals, transgenic mice that allow mutant cells to be visualized in situ were used. These mice carry a defective allele of the human placental alkaline phosphatase (PLAP) gene. The allele does not produce enzyme because the reading frame is shifted by an insertion of 7 G:C basepairs. The insertion is adjacent to four existing G:C basepairs, so the allele has a tract of 11Gs. The G11 PLAP allele was studied in wildtype mice and in mice deficient in mismatch-repair (MMR) due to lack of either Pms2 or Mlh1. PLAP(+) cells were counted in brain, heart, kidney, and liver. In wildtype mice, there was an average of between 5 and 30 PLAP(+) events per million cells. No cells with alkaline phosphatase activity were detected in tissues from mice lacking the PLAP gene. In MMR-deficient mice, the number of PLAP(+) allele was increased by at least three-order of magnitude in brain, heart and kidney, but <10-fold in liver. These data show that MMR is vital to maintaining repeat stability in brain, heart and kidney cells. The reason for the different results in the liver is not clear. Cells in the liver were shown to be capable of expressing of PLAP enzyme and PLAP mRNA was present in this organ.
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Affiliation(s)
- Megan N Hersh
- Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, OH 45267-0524, USA
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